class &SimpleNode
properties
    Next = [];
    Prev = [];
    Data = [];
methods
    function n = SimpleNode(data,prev)
        construct n
        if (nargin > 0)
            n.Data = data;
            if (nargin > 1)
                n.Prev = prev;
                n.Next = prev.Next;
                if ~isempty(n.Next)
                    n.Next.Prev = n;
                end
                prev.Next = n;
            end
        end
    end  % Constructor  
end % Class